Let's Make Robots!

l293d problem

Ok so what does this mean....

 1. the four corner pins are connected to 5v

2. the 2 middle pins on each side of the chip are connect to ground

3. the pins on the outside of the ground pins are connect to the motor

4. the pins on the outside of the motor pins are connected to the inputs.


I have verified those contacts with a multimeter and they are all getting there respective connections and voltages.  

So it is connect correctly.

But when the input pins are driven, one high and one low, the motor doesnt move. I used my multimeter to show that they are being driven high/low. But when i check the outputs, i find that they are not getting voltage. I have tried 2 l293d and i am sure they cant both be not working. What is the problem.



 int out1 =3;

int out2 =4;


void setup(){

  pinMode(out1, OUTPUT);

  pinMode(out2, OUTPUT);



void loop(){


  digitalWrite(out1, HIGH);

  digitalWrite(out2, LOW);


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You're welcome. Remember, you always have to connect all GND (ground) pins together. If you have more than one battery (or source of power) make sure all batteries have common ground. If you connect 2 boards together, make sure you connect the signals AND the GND to both boards. 
In this case, connect pins number 1, 9 and 16 to Arduino +5V pin, all four ground pins to the negative terminal of the battery AND to Arduino GND pin, and connect ONLY pin number 8 to the positive terminal of the battery that will power the motors.

It Works. 

Gosh i love the folks on LMR.

Just need to post my forum on my lcd now. Maybe a similar problem to seperate battery than arduino.

Thanks :D 

 1. the four corner pins are connected to 5v

Make sure that only 3 of the four pins (number 1, 9 and 16) are connected to +5V, the fourth pin has to be connected directly to the battery that will power the motors. This pin is number 8. The rest looks fine to me. Oh, each side controls one motor, so make sure you are connecting the inputs and outputs on the same side.

what do you mean directly to the battery?

the arduino duemilanove is powered via usb and the l293d is hooked to a battery pack.